Cable-type secondary battery

Abstract

A cable-type secondary battery is provided. The cable-type secondary battery includes an electrode assembly and a covering capable of surrounding the electrode assembly. The electrode assembly includes a first polarity electrode, a second polarity electrode, and a separator or an electrolyte layer interposed between the two electrodes. Each of the electrodes has an elongated shape and a structure in which an electrode active material is applied to the surface of a current collector whose shape in cross section orthogonal to the lengthwise direction thereof is circular, elliptical or polygonal. The covering includes a thermally conductive cover member as an upper half part and a thermally insulating cover member as a lower half part. The upper half part and the lower half part are divided by a horizontal plane passing the center of the cross section orthogonal to the lengthwise direction of the cable-type secondary battery.

What is claimed is: 
     
       1. A cable-type secondary battery comprising: an electrode assembly comprising a first polarity electrode, a second polarity electrode, and a separator or an electrolyte layer interposed between the two electrodes, each of the electrodes having an elongated shape and a structure in which an electrode active material is applied to the surface of a current collector whose shape in cross section orthogonal to the lengthwise direction thereof is circular, elliptical or polygonal; and a covering capable of surrounding the electrode assembly,
 wherein the covering comprises a thermally conductive cover member as an upper half part and a thermally insulating cover member as a lower half part, which are divided by a horizontal plane passing the center of the cross section orthogonal to the lengthwise direction of the cable-type secondary battery. 
 
     
     
       2. The cable-type secondary battery according to  claim 1 , wherein the thermally conductive cover member comprises 100 parts by weight of a thermoplastic polymer resin and 20 to 70 parts by weight of a filler. 
     
     
       3. The cable-type secondary battery according to  claim 2 , wherein the thermoplastic polymer resin is selected from the group consisting of polyolefin, polyoxymethylene, polyamide, polysulfone, polyester, polycarbonate, polyvinyl chloride, and mixtures thereof. 
     
     
       4. The cable-type secondary battery according to  claim 2 , wherein the filler is selected from the group consisting of alumina, iron oxide, beryllium oxide, and mixtures thereof. 
     
     
       5. The cable-type secondary battery according to  claim 1 , wherein the thermally insulating cover member comprises at least one polymer selected from the group consisting of polyester, polyamide, polyether sulfone, polyetherimide, polyimide, polyamideimide, polyamide siloxane, polyurethane, polystyrene, polycarbonate and polymethyl methacrylate. 
     
     
       6. The cable-type secondary battery according to  claim 1 , wherein the first polarity electrode is an anode and the second polarity electrode is a cathode. 
     
     
       7. The cable-type secondary battery according to  claim 1 , wherein the electrode material of the first polarity electrode is selected from the group consisting of: carbonaceous materials, comprising natural graphite and artificial graphite; metals (Me), comprising lithium-containing titanium composite oxides (LTO), Si, Sn, Li, Zn, Mg, Cd, Ce, Ni and Fe; alloys of the metals (Me); oxides (MeOx) of the metals (Me); composites of the metals (Me) with carbon; and mixtures thereof. 
     
     
       8. The cable-type secondary battery according to  claim 1 , wherein the electrode material of the second polarity electrode is selected from the group consisting of LiCoO 2 , LiNiO 2 , Li 2 Mn 2 O 4 , LiCoPO 4 , LiFePO 4 , LiNiMnCoO 2 , LiNi 1-x-y-z Co x M1 y M2 z O 2  (wherein M1 and M2 are each independently selected from the group consisting of Al, Ni, Co, Fe, Mn, V, Cr, Ti, W, Ta, Mg and Mo, and x, y and z represent the atomic fractions of the corresponding constituent elements of the oxide and satisfy the relations of 0≦x<0.5, 0≦y<0.5, 0≦z<0.5, x+y+z≦1), and mixtures thereof. 
     
     
       9. The cable-type secondary battery according to  claim 1 , wherein the current collectors of the first and second polarity electrodes are each independently made of stainless steel, aluminum, nickel, titanium, baked carbon, copper, stainless steel surface treated with carbon, nickel, titanium or silver, an aluminum-cadmium alloy, a non-conductive polymer surface treated with a conductive material, or a conductive polymer. 
     
     
       10. The cable-type secondary battery according to  claim 9 , wherein the conductive material is selected from the group consisting of polyacetylene, polyaniline, polypyrrole, polythiophene, poly(sulfur nitride), indium tin oxide (ITO), copper, silver, palladium, nickel, and mixtures thereof. 
     
     
       11. The cable-type secondary battery according to  claim 9 , wherein the conductive polymer is selected from the group consisting of polyacetylene, polyaniline, polypyrrole, polythiophene, poly(sulfur nitride), and mixtures thereof. 
     
     
       12. The cable-type secondary battery according to  claim 1 , wherein the electrolyte layer is formed of an electrolyte selected from: gel-type solid electrolytes using PEO, PVdF, PMMA, PAN or PVAC; and solid polymer electrolytes using PEO, polypropylene oxide (PPO), polyethylene imine (PEI), polyethylene sulphide (PES) or polyvinyl acetate (PVAc). 
     
     
       13. The cable-type secondary battery according to  claim 1 , wherein the electrolyte layer further comprises a lithium salt. 
     
     
       14. The cable-type secondary battery according to  claim 13 , wherein the lithium salt is selected from the group consisting of LiCl, LiBr, LiI, LiClO 4 , LiBF 4 , LiB 10 Cl 10 , LiPF 6 , LiCF 3 SO 3 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiAlCl 4 , CH 3 SO 3 Li, CF 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, chloroborane lithium, lithium lower aliphatic carboxylate, lithium tetraphenylborate, and mixtures thereof.